Conceptually similar to Perl's map keyword. Executes the coderef (in scalar context!) for each match of the path within the object, and sets a new value from the coderef's return value. Within the coderef, $_ may be used to access the old value, and $. may be used to access the curent canonical JSONPath.

JSONPath expressions may contain subexpressions that are evaluated using the native host language. e.g.

$..book[?($_->{author} =~ /tolkien/i)]

The stuff between "?(" and ")" is a Perl expression that must return a boolean, used to filter results. As arbitrary Perl may be used, this is clearly quite dangerous unless used in a controlled environment. Thus, it's disabled by default. To enable, set:

$JSON::Path::Safe = 0;

There are some differences between the JSONPath spec and this implementation.

JSONPath uses a variable '$' to refer to the root node. This is not a legal variable name in Perl, so '$root' is used instead.

JSONPath uses a variable '@' to refer to the current node. This is not a legal variable name in Perl, so '$_' is used instead.

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